The Chinese authorities yesterday received an uncomfortable preview of the scrutiny and criticism likely to accompany the Beijing Olympics this summer as human rights groups hailed Steven Spielberg's withdrawal from his role as an artistic adviser to the games.

Campaign groups vowed to turn their attention to the major Olympic sponsors and other high-profile supporters of the games as they celebrated the international reaction to Spielberg's decision.

The director stepped down from his role as artistic adviser to Beijing late on Tuesday, citing his opposition to China's support for the Sudanese regime responsible for the humanitarian crisis in Darfur. He accused China of not doing enough to press Sudan to end the "continuing human suffering" in the troubled region. China imports two-thirds of Sudan's oil and in return is said to be the African country's biggest arms supplier.

Spielberg's move, taken after months of sustained pressure form his Hollywood peers, led by actor Mia Farrow, apparently took Beijing by surprise.

The state-controlled media pointedly ignored the story and the Beijing organising committee for the Olympic games is understood to be preparing a statement which is likely to be issued this morning.

However, Spielberg's action is bound to anger and alarm the authorities as it comes amid growing complaints about Beijing's record on human rights and Tibet, and is likely to encourage attempts to use the Olympics as leverage on those issues. There is particular concern that the government is cracking down on critics to ensure that they do not embarrass it during the games.

Human rights groups vowed to do just that by targeting other high-profile institutions and individuals: "Olympic corporate sponsors are putting their reputations at risk unless they work to convince the Chinese government to uphold the human rights pledges it made to bring the games to Beijing," said Minky Worden, media director at Human Rights Watch. "Human rights are under attack in China and Olympic sponsors should use their considerable leverage to persuade Beijing to change policy." Major Olympic sponsors include household names such as Coca-Cola, McDonalds and Kodak.

Dr James Smith, chief executive of the Aegis Trust, which campaigns to prevent genocide around the world, said: "This is the biggest message to the Chinese that turning a blind eye to the atrocities in Darfur is unacceptable. Spielberg has demonstrated that collective responsibility means everyone's responsibility."

Spielberg's decision, declared in the pages of the Hollywood journal Variety, comes in a week in which the political ramifications of China's hosting of the games moved to the forefront of public attention. While the Chinese consider the Olympics a coming-out party that will mark their emergence as a major player on the world stage, human rights groups and non-governmental organisations aim to draw attention to Beijing's failings. The arrival of 20,000 journalists in China this summer - two for every athlete - provides opponents of the Chinese government with an unprecedented opportunity to make their case.

Criticism of China's human rights record has coalesced around the issue of Sudan, which Beijing has enthusiastically supported through trade, arms sales and advocacy at the United Nations. More than 200,000 people are thought to have been killed and a further 2.5 million forced from their homes in the five-year conflict between Sudan's Arab-dominated government and Darfur's black African rebels.

Spielberg's announcement coincided with a global day of action in more than a dozen major cities around the world by opponents of the Sudanese regime who called on China to help end the Darfur crisis. The British Olympic Association was forced to rewrite its athletes' contract for Beijing this week after widespread criticism of a clause that barred athletes from discussing "politically sensitive" issues.

Dr David Zweig, director of the Centre on China's Transnational Relations at the Hong Kong University of Science and Technology, said he believed Spielberg's actions would be damaging: "Clearly, Spielberg is a big enough and important enough person that this decision certainly colours the world's view of the Olympics and brings politics front and centre - something the government would have preferred not to see. Internationally, their message is that China is here on the world stage, is a major player and can pull off a world-class event ... they know their international prestige is on the line."

There is deep concern in China that athletes will use the platform of medal success to denounce the country, and at least one campaign group, Team Darfur, is recruiting athletes to do so. British badminton player Richard Vaughan, who hopes to make the Olympic team, said he would defy an attempt at gagging him and speak out about Sudan if asked.

British ministers insisted yesterday that the government would not support any call for a boycott of the Beijing games, but Andy Burnham, the culture secretary, acknowledged that Spielberg had made a point. "He obviously felt very strongly about it and has now very successfully raised the issue," he said. "I don't think you can make a clean separation between representative sport and the situation in any particular country. The world's a complicated place and we have to work together to address those problems."

Downing Street would not comment but the prime minister's official spokesman said last month that Gordon Brown had "no intention of supporting a boycott of the Beijing Olympics".

Ministers believe that the Olympics can spur China to do more on human rights, as well as draw attention to their failings.

Brown argues privately that democracy can emerge slowly in China, but acknowledges that there is work to do. Foreign secretary David Miliband, who is heading to China in the next fortnight for a week-long visit, said in a lecture at Oxford this week: "Now, with the economic success of China, we can no longer take the forward march of democracy for granted." Miliband will meet his Chinese counterpart, Yang Jiechi, for talks. Darfur will be on the agenda.

Brown's officials insist he did raise human rights on his recent two-day visit to Beijing and Shanghai, but details are scarce. Ed Davey, the Liberal Democrats' foreign affairs spokesman, said: "Gordon Brown's silence on human rights and Darfur during his recent Chinese trip stands in sharp contrast to his hand-wringing over Darfur when back in Britain."

The International Olympic Committee maintains that staging the games in China will bring benefits. In December IOC president Jacques Rogge told the Guardian the games would be a "force for good". "But they will not solve all the world's problems."